WO2022046648A1 - Guide de lumière d'imagerie à double entrée - Google Patents

Guide de lumière d'imagerie à double entrée Download PDF

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Publication number
WO2022046648A1
WO2022046648A1 PCT/US2021/047174 US2021047174W WO2022046648A1 WO 2022046648 A1 WO2022046648 A1 WO 2022046648A1 US 2021047174 W US2021047174 W US 2021047174W WO 2022046648 A1 WO2022046648 A1 WO 2022046648A1
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WO
WIPO (PCT)
Prior art keywords
image
diffractive optic
operable
coupling diffractive
bearing light
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PCT/US2021/047174
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English (en)
Inventor
Robert J. Schultz
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Vuzix Corporation
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Publication of WO2022046648A1 publication Critical patent/WO2022046648A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4205—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0081—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means for altering, e.g. enlarging, the entrance or exit pupil
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4272—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having plural diffractive elements positioned sequentially along the optical path
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0016—Grooves, prisms, gratings, scattering particles or rough surfaces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
    • G02B6/0031—Reflecting element, sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055—Reflecting element, sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/262—Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/34—Optical coupling means utilising prism or grating
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/0118—Head-up displays characterised by optical features comprising devices for improving the contrast of the display / brillance control visibility
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/0123—Head-up displays characterised by optical features comprising devices increasing the field of view
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/0123—Head-up displays characterised by optical features comprising devices increasing the field of view
    • G02B2027/0125—Field-of-view increase by wavefront division
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B2027/0178—Eyeglass type
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B2027/0192—Supplementary details
    • G02B2027/0194—Supplementary details with combiner of laminated type, for optical or mechanical aspects
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/286—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another

Definitions

  • the present disclosure relates generally to electronic displays and more particularly to displays utilizing image light guides with diffractive optics to convey image-bearing light to a viewer.
  • Head-Mounted Displays and virtual image near-eye displays are being developed for a range of diverse uses, including military, commercial, industrial, firefighting, and entertainment applications. For many of these applications, there is value in forming a virtual image that can be visually superimposed over the real-world image that lies in the field of view of the HMD user.
  • An optical image light guide may convey imagebearing light to a viewer in a narrow space for directing the virtual image to the viewer's pupil and enabling this superposition function.
  • the present disclosure provides an image light guide for conveying a virtual image includes a substrate operable to propagate image-bearing light beams.
  • a first in-coupling diffractive optic is formed along the substrate, wherein the incoupling diffractive optic is operable to diffract a first portion of the image-bearing light beams from an image source into the substrate in an angularly encoded form, and wherein the first in-coupling diffractive optic is operable to transmit a second portion of the imagebearing light beams from the image source therethrough.
  • An out-coupling diffractive optic is formed along the substrate, wherein the out-coupling diffractive optic is operable to expand the image-bearing light beams and direct the expanded image-bearing light beams from the substrate in an angularly decoded form.
  • a second in-coupling diffractive optic is also formed along the substrate, wherein the second in-coupling diffractive optic is operable to diffract a portion of the second portion of the image-bearing light beams into the substrate in an angularly encoded form.
  • the image light guide further includes an optical coupler located along an axis of the image source, wherein the optical coupler is operable to direct the second portion of image-bearing light from the image source onto the second in-coupling diffractive optic.
  • the present disclosure provides an image light guide system for conveying a virtual image, including an image source operable to project image-bearing light corresponding to a virtual image along a first axis, wherein pixels of the virtual image are infinity focused.
  • the image light guide system also includes a first substrate operable to propagate image-bearing light and a second substrate operable to propagate image-bearing light, wherein the second substrate is coupled with the first substrate.
  • Each of the first and second substrates includes a first in-coupling diffractive optic, a second in-coupling diffractive optic, and an out-coupling diffractive optic.
  • the out- coupling diffractive optic is operable to expand the image-bearing light and direct the expanded image-bearing light from the substrate.
  • the image light guide system further includes an optical coupler located along the first axis, wherein the optical coupler is located at least partially along a path of image-bearing light transmitted through the first in-coupling diffractive optics of said first and second substrates.
  • the optical coupler is operable to direct the image-bearing light onto the second in-coupling diffractive optic of the second substrate, wherein the second in-coupling diffractive optic is operable to diffract a portion of the imagebearing light into the second substrate in an angularly encoded form and transmit a portion of the image-bearing light beams toward the second in-coupling diffractive optic of the first substrate, wherein the second in-coupling diffractive optic of the first substrate is operable to diffract a portion of the image-bearing light into the first substrate in an angularly encoded form.
  • FIG. 1 shows a simplified cross-sectional view of an image light guide showing the expansion of an image-bearing beam along the direction of propagation for expanding one direction of an eyebox.
  • FIG. 2 shows a perspective view of an image light guide with a turning grating showing the expansion of an image-bearing beam perpendicular to the direction of propagation for expanding a second direction of an eyebox.
  • FIG. 3 shows a schematic plan view of an image light guide having dual in-coupling diffractive optics according to an exemplary embodiment of the presently disclosed subject matter.
  • FIG. 4 shows a schematic side view of the image light guide according to FIG. 3 having an optical coupler according to an exemplary embodiment of the presently disclosed subject matter.
  • FIG. 5 A shows a schematic end view of the image light guide according to FIG. 4 having two in-coupling diffractive optics located on a first surface.
  • FIG. 5B shows a schematic end view of the image light guide according to FIG. 4 having a first in-coupling diffractive optic located on a first surface and a second in-coupling diffractive optic located on a second surface.
  • FIG. 5C shows a schematic end view of the image light guide according to FIG. 4 having a first in-coupling diffractive optic located on a second surface and a second incoupling diffractive optic located on a first surface.
  • FIG. 5D shows a schematic end view of the image light guide according to FIG. 4 having a first in-coupling diffractive optic located on a second surface and a second incoupling diffractive optic located on the second surface.
  • FIG. 6 shows a schematic perspective view of the image light guide according to FIG. 4.
  • FIG. 7A shows a schematic perspective view of the optical coupler according to FIG. 4.
  • FIG. 7B shows a schematic end view of the optical coupler according to FIG. 4 wherein the first surface comprises a mirror.
  • FIG. 8A shows a schematic end view of an image light guide according to FIG. 4
  • FIG. 8B shows a schematic end view of an image light guide according to FIG. 8A having the planar waveguide rotated about an axis.
  • FIG. 9 shows a schematic top view of the optical coupler according to FIG. 4.
  • FIGS. 10A and 10B show a schematic of a portion of periodic diffraction gratings according to an exemplary embodiment of the presently disclosed subject matter.
  • FIG. 11 shows schematic end view of a stacked imaging light guide system according to an exemplary embodiment of the presently disclosed subject matter.
  • FIG. 12 shows a schematic side view of the stacked imaging light guide system according to FIG. 11.
  • FIG. 13 shows a display system for augmented reality viewing using imaging light guides according to an exemplary embodiment of the presently disclosed subject matter.
  • viewer refers to the person/machine that views images using a device having an imaging light guide.
  • set refers to a non-empty set, as the concept of a collection of elements or members of a set is widely understood in elementary mathematics.
  • subset refers to a non- empty proper subset, that is, to a subset of the larger set, having one or more members.
  • a subset may comprise the complete set S.
  • a “proper subset” of set S is strictly contained in set S and excludes at least one member of set S.
  • Coupled in the context of optics refer to a connection by which light travels from one optical medium or device to another optical medium or device.
  • beam expansion expansion of an image-bearing beam
  • expansion of image-bearing light are intended to mean replication of a beam via multiple encounters with an optical element to provide exit pupil expansion in one or more directions.
  • expand a beam, or a portion of a beam, is intended to mean replication of a beam via multiple encounters with an optical element to provide exit pupil expansion in one or more directions.
  • An optical system such as a HMD, can produce a virtual image.
  • a virtual image is not formed on a display surface. That is, if a display surface were positioned at the perceived location of a virtual image, no image would be formed on that surface.
  • Virtual images have a number of inherent advantages for augmented reality presentation. For example, the apparent size of a virtual image is not limited by the size or location of a display surface. Additionally, the source object for a virtual image may be small; for example, a magnifying glass provides a virtual image of an object. In comparison with systems that project a real image, a more realistic viewing experience can be provided by forming a virtual image that appears to be some distance away. Providing a virtual image also obviates the need to compensate for screen artifacts, as may be necessary when projecting a real image.
  • An image light guide may utilize image-bearing light from a light source such as a projector to display a virtual image.
  • a light source such as a projector
  • collimated, relatively angularly encoded, light beams from a projector are coupled into a planar waveguide by an input coupling such as an in-coupling diffractive optic, which can be mounted or formed on a surface of the planar waveguide or buried within the waveguide.
  • diffractive optics can be formed as diffraction gratings, holographic optical elements (HOE’s) or in other known ways.
  • the diffraction grating can be formed by surface relief After propagating along the waveguide, the diffracted light can be directed back out of the waveguide by a similar output coupling such as an out-coupling diffractive optic, which can be arranged to provide pupil expansion along one direction.
  • a turning grating can be positioned on/in the waveguide to provide pupil expansion in an orthogonal direction. The image-bearing light output from the waveguide provides an expanded eyebox for the viewer.
  • an image light guide 10 may comprise a planar waveguide 22 having plane-parallel surfaces.
  • the waveguide 22 comprises a transparent substrate S having an outer surface 12 and an inner surface 14 located opposite the outer surface 12.
  • an in-coupling diffractive optic IDO and an out-coupling diffractive optic ODO are arranged on the inner surface 14 and the in-coupling diffractive optic IDO is a reflective type diffraction grating through which image-bearing light WI is coupled into the planar waveguide 22.
  • the in-coupling diffractive optic IDO could alternately be a transmissive type diffraction grating, volume hologram or other holographic diffraction element, or other type of optical component that provides diffraction for the incoming, image-bearing light WI.
  • the in-coupling diffractive optic IDO can be located on the outer surface 12 or the inner surface 14 of the planar waveguide 22 and can be of a transmissive or reflective type in a combination that depends upon the direction from which the imagebearing light WI approaches the planar waveguide 22.
  • the in-coupling diffractive optic IDO couples the image-bearing light WI from an image source into the substrate S of the planar waveguide 22. Any real image or image dimension is first converted into an array of overlapping angularly related beams encoding the different positions within a virtual image for presentation to the in-coupling diffractive optic IDO.
  • the image-bearing light WI is diffracted (generally through a first diffraction order) and thereby redirected by in-coupling diffractive optic IDO into the planar waveguide 22 as image-bearing light WG for further propagation along the planar waveguide 22 by Total Internal Reflection (“TIR”).
  • TIR Total Internal Reflection
  • the image-bearing light WG preserves the image information in an encoded form.
  • the out-coupling diffractive optic ODO receives the encoded image-bearing light WG and diffracts (also generally through a first diffraction order) the image-bearing light WG out of the planar waveguide 22 as the image-bearing light WO toward the intended location of a viewer’s eye.
  • the out-coupling diffractive optic ODO is designed symmetrically with respect to the in-coupling diffractive optic IDO to restore the original angular relationships of the image-bearing light WI among outputted angularly related beams of the image-bearing light WO.
  • the out-coupling diffractive optic ODO is arranged to encounter the image-bearing light WG multiple times and to diffract only a portion of the image-bearing light WG on each encounter.
  • the multiple encounters along the length of the out-coupling diffractive optic ODO in the direction of propagation have the effect of expanding one direction of the eyebox E within which the beams overlap.
  • the expanded eyebox E decreases sensitivity to the position of a viewer’s eye for viewing the virtual image.
  • the out-coupling diffractive optic ODO is a transmissive type diffraction grating arranged on the inner surface 14 of the planar waveguide 22.
  • the out-coupling diffractive optic ODO can be located on the outer surface 12 or the inner surface 14 of the planar waveguide 22 and be of a transmissive or reflective type in a combination that depends upon the direction through which the image-bearing light WG is intended to exit the planar waveguide 22.
  • an image light guide 20 may be arranged for expanding an eyebox 74 in two directions, i.e., along both x- and y-axes of the intended image.
  • the in-coupling diffractive optic IDO is oriented to diffract the image-bearing light WG about a grating vector kO toward an intermediate turning grating TG whose grating vector kl is oriented to diffract the image-bearing light WG in a reflective mode toward the out-coupling diffractive optic ODO.
  • the turning grating TG redirects the image-bearing light WG into an at least approximate alignment with a grating vector k2 of the out-coupling diffractive optic ODO for longitudinally expanding the angularly related beams of the image-bearing light WG in a second direction before exiting the planar waveguide 22 as the image-bearing light WO.
  • Grating vectors such as the depicted grating vectors kO, kl, k2, extend in a direction that is normal to the diffractive features (e.g., grooves, lines, or rulings) of the diffractive optics and have a magnitude inverse to the period or pitch d (i.e., the on-center distance between grooves) of the diffractive optics IDO, TG, ODO.
  • the in-coupling diffractive optic IDO receives the incoming image-bearing light WI containing a set of angularly related beams corresponding to individual pixels or equivalent locations within an image generated by an image source 16.
  • the image source 16 operable to generate a full range of angularly encoded beams for producing a virtual image, may be, but is not limited to, a real display together with focusing optics, a beam scanner for more directly setting the angles of the beams, or a combination such as a one-dimensional real display used with a scanner.
  • the image light guide 20 outputs an expanded set of angularly related beams in two directions by providing multiple encounters of the image-bearing light WG with both the intermediate turning grating TG and the out-coupling diffractive optic ODO in different orientations.
  • the intermediate grating TG provides beam expansion in the y-axis direction
  • the out-coupling diffractive optic ODO provides a similar beam expansion in the x-axis direction.
  • the reflectivity characteristics and respective periods d of the diffractive optics IDO, ODO, TG, together with the orientations of their respective grating vectors, provide for beam expansion in two directions while preserving the intended relationships among the angularly related beams of the image-bearing light WI that are output from the image light guide 20 as the image-bearing light WO.
  • the image-bearing light WI input into the image light guide 20 is encoded into a different set of angularly related beams by the in-coupling diffractive optic IDO, the information required to reconstruct the image is preserved by accounting for the systematic effects of the in-coupling diffractive optic IDO.
  • the turning grating TG located in an intermediate position between the in-coupling and out-coupling diffractive optics IDO, ODO, is typically arranged so that it does not induce any significant change on the encoding of the image-bearing light WG.
  • the out-coupling diffractive optic ODO is typically arranged in a symmetric fashion with respect to the in-coupling diffractive optic IDO, e.g., including diffractive features sharing the same period.
  • the period of the turning grating TG also typically matches the common period of the in-coupling and out-coupling diffractive optics IDO, ODO.
  • the grating vector kl of the turning grating TG may be oriented at 45 degrees with respect to the other grating vectors kO, k2 (all as undirected line segments).
  • the grating vector kl of the turning grating TG is oriented at 60 degrees to the grating vectors kO, k2 of the in-coupling and out- coupling diffractive optics IDO, ODO in such a way that the image-bearing light WG is turned 120 degrees.
  • the grating vectors kO, k2 are also oriented at 60 degrees with respect to each other (again considered as undirected line segments).
  • the three grating vectors kO, kl, k2 (as directed line segments) form an equilateral triangle, and sum to a zero-vector magnitude, which avoids asymmetric effects that could introduce unwanted aberrations including chromatic dispersion.
  • the image-bearing light WI that is diffracted into the planar waveguide 22 is effectively encoded by the in-coupling diffractive optic IDO, whether the in-coupling diffractive optic IDO uses gratings, holograms, prisms, mirrors, or some other mechanism. Any reflection, refraction, and/or diffraction of light that takes place at the in-coupling diffractive optic IDO must be correspondingly decoded by the out-coupling diffractive optic ODO to re-form the virtual image that is presented to the viewer.
  • the turning grating TG placed at an intermediate position between the in-coupling and out-coupling diffractive optics IDO, ODO, is typically designed and oriented so that it does not induce any change on the encoded light.
  • the out-coupling diffractive optic ODO decodes the image-bearing light WG into its original or desired form of angularly related beams that have been expanded to fill the eyebox 74.
  • the turning grating TG and the in-coupling and out-coupling diffractive optics IDO, ODO are related so that the image-bearing light WO that is output from the planar waveguide 22 preserves or otherwise maintains the original or desired form of the image-bearing light WI for producing the intended virtual image.
  • the letter “R” represents the orientation of the virtual image that is visible to the viewer whose eye is in the eyebox 74. As shown, the orientation of the letter “R” in the represented virtual image matches the orientation of the letter “R” as encoded by the imagebearing light WI.
  • a change in the rotation about the z axis or angular orientation of incoming image-bearing light WI with respect to the x-y plane causes a corresponding symmetric change in rotation or angular orientation of outgoing light from out-coupling diffractive optic ODO.
  • the turning grating TG simply acts as a type of optical relay, providing expansion of the angularly encoded beams of the image-bearing light WG along one axis (e.g., along the y-axis) of the image.
  • the out-coupling diffractive optic ODO further expands the angularly encoded beams of the image-bearing light WG along another axis (e.g., along the x-axis) of the image while maintaining the original orientation of the virtual image encoded by the image-bearing light WI.
  • the turning grating TG may be a slanted or square grating arranged on the front or back surfaces of the planar waveguide 22. Alternately, the turning grating TG may be a blazed grating.
  • the present disclosure provides for an image light guide arrangement having improved image-bearing light output intensity across the output aperture. More specifically, the present disclosure provides for, inter aha, a waveguide having more than one in-coupling diffractive optic and an out-coupling diffractive optic operable to expand image-bearing light beams in two-directions and output the expanded image-bearing light beams toward an eyebox.
  • an image light guide 100 may have a first incoupling diffractive optic IDO1, a second in-coupling diffractive optic IDO2, and an out- coupling diffractive optic ODO formed on/in a first surface 102 of the planar waveguide 22.
  • the first in-coupling diffractive optic IDO1 and the out-coupling diffractive optic ODO are formed on/in the first surface 102 of the planar waveguide 22, and the second in-coupling diffractive optic IDO2 is formed on/in the second surface 104 of the planar waveguide 22 located opposite the first surface 102.
  • FIG. 5B the first in-coupling diffractive optic IDO1 and the out-coupling diffractive optic ODO are formed on/in the first surface 102 of the planar waveguide 22
  • the second in-coupling diffractive optic IDO2 is formed on/in the second surface 104 of the planar waveguide 22 located opposite the first surface 102.
  • the first in-coupling diffractive optic IDO1 is formed on/in the second surface 104 of the planar waveguide 22, and the second in-coupling diffractive optic IDO2 and the out-coupling diffractive optic ODO are located on/in the first surface 102 of the planar waveguide 22.
  • the first and second in-coupling diffractive optics IDO1, IDO2 are formed on/in the second surface 104 of the planar waveguide 22, and the out-coupling diffractive optic ODO is located on/in the first surface 102 of the planar waveguide 22.
  • the first and second in-coupling diffractive optics IDO1, IDO2 and the out-coupling diffractive optic ODO are formed on/in the second surface 104 of the planar waveguide 22.
  • the first and second in-coupling diffractive optics IDO1, IDO2 comprise two pluralities of periodic grating structures 106, 108.
  • the in-coupling diffractive optic IDO may comprise a first set of periodic linear grating structures 106 rotated/ offset relative to the x-axis by an angle less than thirty degrees (e.g., 25°), and a second set of periodic linear grating structures 108 rotated/offset relative to the x-axis by an angle less than negative thirty degrees (e.g., -25°).
  • the first and second sets of periodic grating structures 106, 108 are crossed.
  • the first set of periodic grating structures 106 comprises a first period
  • the second set of periodic grating structures 108 comprise a second period. In an embodiment, the second period is equal to the first period.
  • the out-coupling diffractive optic ODO comprises third and fourth sets of periodic grating structures 110, 112.
  • the third and fourth sets of periodic grating structures 110, 112 are parallel with the first and second sets of periodic grating structures 106, 108, respectively.
  • the third and fourth sets of periodic grating structures 110, 112 form a compound diffractive optic operable to expand and out-couple image-bearing light from the in-coupling diffractive optics IDO1, IDO2.
  • the third set of periodic grating structures 110 is crossed with the fourth set of periodic grating structures 112.
  • the third and fourth sets of periodic grating structures 110, 112 may also have the same periodicity as the first and second sets of periodic grating structures 106, 108, respectively.
  • the out-coupling diffractive optic ODO has bilateral symmetry across a longitudinal axis 115.
  • the image light guide 100 includes an optical coupler 120.
  • the optical coupler 120 is located adjacent to the in-coupling diffractive optics IDO1, IDO2 on an opposite side of the planar waveguide 22 from a projector 16 (i.e., image source).
  • the optical coupler 120 includes a first surface 122 located generally proximal to the planar waveguide 22.
  • the optical coupler 120 also includes a second surface 124 disposed at an angle a relative to the first surface 122, and a bilaterally symmetric third surface 126 disposed at an angle a relative to the first surface 122.
  • the optical coupler 120 is assembled from two right angle prisms 120A, 120B.
  • the second and third surfaces 124, 126 are mirrored surfaces.
  • the first surface 122 is the incident face of the optical coupler 120 and receives image-bearing light from the projector 16 along a first axis Al.
  • the first axis Al is aligned with a center ray of the projector 16.
  • the image-bearing light reflects from the second surface 124 back toward the first surface 122 within the TIR angle range.
  • the first surface 122 is operable to reflect the image-bearing light under TIR, and the image-bearing light reflected from the second surface 124 is reflected by the first surface 122 toward the third surface 126.
  • the third surface 126 further reflects the image-bearing light toward the first surface 122 within an angle range operable to transmit through the first surface 122.
  • the image-bearing light is output from the optical coupler 120 centered along a second axis A2.
  • the second axis A2 is aligned with a center ray output from the optical coupler 120.
  • the second axis A2 is offset from the first axis Al along the y-axis direction. Designing the optical coupler 120 to have three points of reflection within the optical coupler 120 prevents the virtual image of the image-bearing light incident upon the optical coupler 120 from being flipped.
  • image-bearing light WI from the projector 16 is incident upon the first in-coupling diffractive optic IDO1, a first portion of the image-bearing light WG1 is diffracted by the first in-coupling diffractive optic IDO1 and generally propagates toward the out-coupling diffractive optic ODO via TIR.
  • a second portion of the image-bearing light WI transmits through the first in-coupling diffractive optic IDO1 and the planar waveguide 22 and is incident upon the optical coupler 120.
  • the second portion of the image-bearing light WI transmits through the first surface 122 of the optical coupler 120 and reflects from the second surface 124 of the optical coupler at an angle of incidence operable to reflect from the first surface 122 via TIR.
  • the second portion of the image-bearing light WI is then reflected from the first surface 122 under TIR and is incident upon the third surface 126 of the optical coupler where the second portion of the image-bearing light WI is reflected back toward the first surface 122 and transmitted therethrough along the second axis A2.
  • the second portion of the image-bearing light WI centered along the second axis A2 is then incident upon the second in-coupling diffractive optic IDO2.
  • a portion of the second portion of the image-bearing light WG2 is diffracted by the second in-coupling diffractive optic IDO2 and generally propagates toward the out-coupling diffractive optic ODO via TIR.
  • the second in-coupling diffractive optic IDO2 is configured to optimize diffractive efficiency for image-bearing light output from the optical coupler 120.
  • the first in-coupling diffractive optic IDO1 may be configured as a transmissive type diffraction grating and the second in-coupling diffractive optic IDO2 may be configured as a reflective type diffraction grating.
  • the first and second sets of periodic grating structures 106, 108 are surface-relief gratings
  • the first and second sets of periodic grating structures 106, 108 are slanted at a slant angle ⁇
  • the first set of periodic grating structures 106 of the first in-coupling diffractive optic IDO1 may have a slant angle ⁇
  • the second set of periodic grating structures 108 of the first in-coupling diffractive optic IDO1 may have a slant angle ⁇
  • the periodic grating structures 106, 108 of the first and second in-coupling diffractive optics IDO1, IDO2 may have slant angles ⁇
  • the imaging light guide 100 is operable to in-couple a greater percentage of the imagebearing light from the projector 16. Increasing the percentage of the image-bearing light from the projector 16 which is in-coupled to the planar waveguide 22 increases the brightness of the virtual image viewed in an eyebox.
  • the first surface 122 of the optical coupler 120 may include a mirrored surface 132.
  • the mirrored surface 132 may be formed on the first surface 122 such that the second portion of image-bearing light reflected from the second surface 124 is incident upon the mirrored surface 132.
  • the mirrored surface 132 may be formed by applying an at least partially reflective coating to a portion of the optical coupler first surface 122. Image-bearing light from the image source 16 that is incident upon a first portion 122A of the optical coupler first surface 122 is transmitted therethrough and is incident upon the second surface 124.
  • Image-bearing light reflected from the second surface 124 is incident upon a second portion 122B of the first surface 122 having the mirrored surface 132 and is reflected toward the third surface 126.
  • Image-bearing light reflected from the second portion 122B of the first surface 122 is incident upon the third surface 126 and is reflected toward a third portion 122C of the first surface 122.
  • Image-bearing light incident upon the third portion 122C of the first surface 122 is transmitted therethrough.
  • the imaging light guide 100 may include a waveplate 130 located between the optical coupler 120 and the planar waveguide 22.
  • the length of the waveplate 130 is less than the length of the optical coupler 120, such that light transmitted through the planar waveguide 22 and incident upon the first surface 122 of the optical coupler 120 does not transmit through the waveplate 130, while image-bearing light reflected from the third surface 126 and transmitted through the first surface 122 of the optical coupler 120 is transmitted through the waveplate 130.
  • the waveplate 130 is operable to turn the polarization direction of the image-bearing light such that the imaging light guide 100 takes full advantage of the image-bearing light from the projector 16.
  • the waveplate 130 may be a half-wave waveplate operable to turn the polarization direction of the image-bearing light orthogonal (90°) or nearly orthogonal.
  • the waveplate 130 may be a quarter-wave waveplate operable to turn the polarization direction of the image-bearing light generally forty -five degrees (45°).
  • Transmissive type diffraction gratings have lower polarization sensitivity than reflective type diffraction gratings.
  • the second in-coupling diffractive optic IDO2 is a reflective type diffraction grating, polarization of the image-bearing light via the half-wave waveplate 130 enables a greater diffraction efficiency.
  • the projector 16 comprises a digital light processing (“DLP”) projector operable to output unpolarized light.
  • DLP digital light processing
  • the image light guide 100 may produce two misaligned virtual images.
  • an imperfection in the optical coupler 120 may cause the image-bearing light WG2 to be incident upon the second incoupling diffractive optic IDO2 at an angle relative to the second axis A2; this angle of incidence is mirrored in angle of the second out-going light beam WO2 relative to the second axis A2 causing misalignment of the two virtual images.
  • FIG. 8A an imperfection in the optical coupler 120 may cause the image-bearing light WG2 to be incident upon the second incoupling diffractive optic IDO2 at an angle relative to the second axis A2; this angle of incidence is mirrored in angle of the second out-going light beam WO2 relative to the second axis A2 causing misalignment of the two virtual images.
  • the planar waveguide 22 may be rotated, or rocked, about the x-axis and/or the y-axis to align the two virtual images produced by the image light guide 100.
  • Rotating the planar waveguide 22 relative to the projector 16 and the optical coupler 120 compensates for the effect of the imperfections in alignment of the center ray of an image-bearing light beam WG2 in-coupled into the planar waveguide 22 via the second in-coupling diffractive optic IDO2 and out- coupled via the out-coupling diffractive optic ODO.
  • Rotating the planar waveguide 22 about the center of the first in-coupling diffractive optic IDO1 allows the second out-going light beam WO2 to be repositioned relative to the second in-coupling diffractive optic IDO2, without changing the center ray position of the first out-going light beam WO1 relative to the center of the first diffractive optic IDO1.
  • rocking the planar waveguide 22 aligns the central ray of image-bearing light beams WO1, WO2 generally parallel with respect to one another. This feature allows for a greater tolerance in the alignment of the projector 16 and the optical coupler 120.
  • a stacked image light guide assembly 400 includes a first image light guide 402 coupled with a second image light guide light guide 404. At least one of the first image light guide 402 and the second image light guide 404 is one of the image light guides 100 described supra.
  • the image light guides 402, 404 are formed on separate waveguide substrates 22 that are mechanically coupled. In an embodiment, the waveguide substrates 22 of the image light guides 402, 404 are mechanically coupled via an adhesive.
  • the waveguide substrates 22 are held in position relative to one another by structural means of the HMD.
  • the waveguide substrates 22 may be held in relative position via the glasses rims.
  • the stacked image light guide assembly 400 provides three separate color channels. A first portion of the image-bearing light WI from the projector 16 that is incident upon the first in-coupling diffractive optic IDO1 of the first image light guide 402 is diffracted and propagates toward the out-coupling diffractive optic ODO of the first image light guide 402 via TIR.
  • a second portion of the image-bearing light WI that is incident upon the first-in- coupling diffractive optic of the first image light guide 402 is transmitted therethrough and is incident upon the first in-coupling diffractive optic IDO1 of the second image light guide 404.
  • a portion of the image-bearing light WG2 that is incident upon the first in-coupling diffractive optic IDO1 of the second image light guide 404 is diffracted and propagates toward the out-coupling diffractive optic ODO of the second image light guide 404 via TIR.
  • a third portion of the image-bearing light WI is transmitted through the in-coupling diffractive optic IDO1 of the second image light guide 404 and is incident on the optical coupler 120 as described above.
  • the third portion of the image-bearing light WI is then output from the optical coupler 120 centered along the second axis A2 and is incident upon the second in-coupling diffractive optic IDO2 of the second image light guide 404.
  • a portion of the image-bearing light WG3 that is incident upon the second in-coupling diffractive optic IDO2 of the second image light guide 404 is diffracted and propagates toward the out- coupling diffractive optic ODO of the second image light guide 404 via TIR.
  • a fourth portion of the image-bearing light WI is transmitted through the second in-coupling diffractive optic IDO2 of the second image light guide 404 and is incident on the second incoupling diffractive optic IDO2 of the first image light guide 402.
  • a portion of the imagebearing light WG4 that is incident upon the second in-coupling diffractive optic IDO2 of the first image light guide 402 is diffracted and propagates toward the out-coupling diffractive optic ODO of the first image light guide 402 via TIR.
  • the image-bearing light WG1, WG2, WG3, WG4 that is incident upon the out-coupling diffractive optics ODO of the first and second image light guides 402, 404 is expanded and out-coupled toward an eyebox as imagebearing light WO.
  • FIG. 13 shows a display system 60 for augmented reality viewing using one or more image light guides of the present disclosure.
  • Display system 60 is shown as an HMD with a right-eye optical system 64R having an image light guide 66R for the right eye.
  • the display system 60 includes an image source 68, such as a picoprojector or similar device, energizable to generate an image.
  • the display system 60 includes a left-eye optical system including one or more image light guides and a second image source.
  • the images that are generated can be a stereoscopic pair of images for 3-D viewing.
  • the virtual image that is formed by the display system 60 can appear to be superimposed or overlaid onto the real-world scene content seen by the viewer through an image light guide 66R.
  • Additional components familiar to those skilled in the augmented reality visualization arts, such as one or more cameras mounted on the frame of the HMD for viewing scene content or viewer gaze tracking, can also be provided.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)

Abstract

L'invention concerne un guide de lumière d'image pour produire une image virtuelle comprenant un substrat utilisable pour propager des faisceaux lumineux portant des images. Une première optique diffractive de couplage d'entrée est formée le long du substrat, et peut fonctionner pour diffracter une première partie des faisceaux lumineux portant des images provenant d'une source d'image dans le substrat sous une forme codée angulairement, ainsi que pour transmettre une seconde partie des faisceaux lumineux portant des images à partir de la source d'image. Une optique diffractive de couplage de sortie est formée le long du substrat, l'optique de diffraction de couplage de sortie pouvant fonctionner pour étendre les faisceaux lumineux portant des images et diriger les faisceaux lumineux portant des images étendus à partir du substrat sous une forme décodée angulairement. Une seconde optique diffractive de couplage d'entrée est formée le long du substrat et peut fonctionner pour diffracter une partie de la seconde partie de faisceaux lumineux portant des images dans le substrat sous une forme codée angulairement.
PCT/US2021/047174 2020-08-24 2021-08-23 Guide de lumière d'imagerie à double entrée WO2022046648A1 (fr)

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WO2023192650A1 (fr) * 2022-03-31 2023-10-05 Vuzix Corporation Système de guidage de lumière d'imagerie à plage de longueurs d'onde multiples
WO2024073100A1 (fr) * 2022-09-30 2024-04-04 Vuzix Corporation Système de projecteur double et guide de lumière d'image

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JP7524460B2 (ja) 2024-07-29
WO2022046789A1 (fr) 2022-03-03
CN116097152A (zh) 2023-05-09
EP4172686A4 (fr) 2024-07-31
EP4172686A1 (fr) 2023-05-03
US20230341685A1 (en) 2023-10-26
JP2023537869A (ja) 2023-09-06

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